To create a bootable USB key from an .iso image on OS X so that a machine with the ability to boot from USB keys can boot it, you need to first create an .img file from the .iso file you downloaded.
Tip: Drag and drop a file from Finder to Terminal to ‘paste’ the full path without risking typing errors.
Open the Terminal and type the following command to convert the .iso file to .img using the convert option of hdiutil e.g.,
hdiutil convert -format UDRW -o ~/path/to/target.img ~/path/to/downloaded.iso |
Note: OS X tends to put the .dmg ending on the output file automatically.
Run
diskutil list |
to get the current list of devices.
Insert your flash media.
Run
diskutil list |
again and determine the device node assigned to your flash media (e.g. /dev/disk2).
Run
diskutil unmountDisk /dev/diskN |
(replace N with the disk number from the last command; in the previous example, N would be 2).
Execute
sudo dd if=/path/to/downloaded.img of=/dev/rdiskN bs=1m |
- Using /dev/rdisk instead of /dev/disk may be faster
- If you see the error dd: Invalid number ‘1m’, you are using GNU dd. Use the same command but replace bs=1m with bs=1M
- If you see the error dd: /dev/diskN: Resource busy, make sure the disk is not in use. Start the ‘Disk Utility.app’ and unmount (don’t eject) the drive
- To see progress you can type ctrl-t
Run
diskutil eject /dev/diskN |
and remove your flash media when the command completes.